1. Field of the Invention
The present invention relates to a braking force control system and method of a vehicle for properly applying braking force to wheels so as to make a stable and smooth turn when cornering.
2. Prior Arts
In recent years, due to an increasing concern about vehicle safety, many techniques for safe driving have been developed. Among them, there are several proposed technologies in which when a vehicle turns corners, an optimally controlled braking force is applied to wheels based on vehicle driving conditions data for accomplishing a stable and smooth cornering of the vehicle.
For example, Japanese Unexamined Patent Application Toku-Kai-Hei 2-70561 discloses a braking force control apparatus for controlling braking force on the basis of a yaw rate or an angular velocity of yawing, i.e., a rotational motion about a vertical axis passing through a center of gravity of the vehicle. In this technology, it is judged whether the vehicle is turning in an under-steer condition or in an over-steer condition with respect to a target yaw rate by comparing an actual yaw rate with the target yaw rate and if the vehicle is in an under-steer condition, braking force is applied to inner wheels (wheels on the side of a turning center) to correct under-steer such that a deviation of the actual yaw rate from the target yaw rate is minimized and if the vehicle is in an over-steer condition, braking force is applied to outer wheels (wheels on the opposite side of a turning center) to correct over-steer.
In this technique, however, since the system is constituted such that a running stability of the vehicle is always restored by applying braking force to a proper wheel, it is difficult to give an intentional turn to the vehicle in such a case where a driver tries to avoid an obstacle by way of an operation other than steering, for example, an accelerator pedal operation.